Arithmetic Micro-Operations

Arithmetic micro-operations constitute two varieties of among of which, one are BASIC Arithmetic Micro-operations and second are DERIVED Arithmetic Micro-operations.

Simple operations like ADDITION, SUBTRACTION, COMPLEMENTATION etc. are considered as BASIC micro-operations while MULTIPLICATION and DIVISION are the operations that undergo DERIVED Micro-operations.

Multi-bit Binary Adder:

A Multi-bit binary adder is simply a series of “n�, 1-bit full adders cascaded together with each full adder representing a single weighted column in a long binary addition. It is often called a ripple carry adder because the carry signals produce a “ripple� effect through the binary adder from right to left, (LSB to MSB).

Multi-bit Binary Adder/Subtractor:

A multi-bit adder-subtractor uses the same circuit of cascaded FULL ADDERS. This circuit adds in the same way as the multi-bit adder, but subtracts using the twos complement method.

When subtraction is required, the C0 is set to logic 1, which causes the bit at any particular B input to be complemented by an XOR gate before being fed to input B of the full adder circuit.

Multi-bit Binary incrementer:

The binary incrementer increases the value stored in a register by ‘1’. For this, it simply adds ‘1’ to the existing value stored in a register. It is made by cascading ‘n’ half adders for ‘n’ number of bits i.e. the storage capacity of the register to be incremented. Hence, a 4-bit binary incrementer requires 4 cascaded half adder circuits.